Hi, gold leaf, bout 7 weeks old. Coco base soil, g...

possibly genetics, possibly environmental causes... or a combination... if temperatures get below ~68F, you can often see color come out in leaves. it's not necessarily a bad thing. Get a space heater in there if you can, or in the room the tent resides in. somethign with a thermostat so you can keep it above 68F at night or whenver lights are off -- assuming lights add some warmth to keep it above that threshold while on. purple stems can indicated a need for magnesium. Nearly all plants i have end up with red/purple petioles. Think it's related to LED lighting, but can also be a symptom. Ensure pH is ~6.5. Review what you have fed.. calculate PPMs... this will all help you deduce if there is any underlying factor that is more of a concern and avoid it worsening. if it is a well-balanced diet, it is not likely the nutes.